1. Field of the Invention
The present invention pertains to an insert rotary cutter for use in shoulder cutting operation, and more particularly to such a cutter having an indexable cutter insert of a generally triangular shape.
2. Prior Art
FIGS. 1 to 4 depict a conventional insert rotary cutter for effecting shoulder cutting operation. The cutter includes a cutter body 100 of a generally circular cross-section and a plurality of indexable cutter inserts 102 of a triangular shape each releasably attached to the cutter body 100. Each insert 102 is received in a support member 104 and secured thereto through a wedge 106 fixed to the cutter body 100 by a clamp screw 108.
As seen best in FIG. 2, the triangular cutter insert 102 includes three indexable sets of main, corner, and auxiliary cutting edges 110, 112 and 114, and hence is economical as compared with parallelogramic or rhombic cutter inserts. However, since the apex angle of the insert 102 is 60.degree. as depicted in FIG. 2, strength of the portion adjacent to the auxiliary cutting edge 114 is relatively small, so that the portion is susceptible to chipping. In addition, a wiper insert should preferably be employed to improve the surface finish of the machined product. However, a conventional wiper insert has a shape such as parallelogram and hence is quite different from the above triangular insert. For this reason, when replacing the above usual insert with a wiper insert, the support member 104 must also be replaced with a different one. Thus, a shoulder cutter with a wiper insert has not hitherto been put to practical use.